The present invention relates generally to an engine-generator set (genset), and, more particularly, to an operation of the genset during transient conditions.
Gensets are used to supply electrical power in places where utility (central station) power is not available, or where power is needed only temporarily. Currently, gensets typically include engines connected directly to generators to produce electricity. In some cases the generators are permanently installed and kept ready to supply power to critical loads during temporary interruptions of the utility power supply. Typically the gensets operate at a fixed speed to produce electricity at a grid frequency. The fixed speed may typically be 1500 rpm for a 50 Hz grid frequency or 1800 (or 1200) rpm for a 60 Hz grid frequency.
For low power engines, such as engines operating below about 25 KW, higher speeds are typically possible as are higher output power and higher efficiency. However, operation of the engine at very high speeds is not practical when the genset needs to generate electricity at a fixed grid frequency. In some cases, the output power required from the genset is below a rated value while the engine is still running at a fixed speed. This results in reduction in the engine efficiency. In islanded grids, the engine efficiency may be improved by reducing the engine speed and hence reducing the fuel consumption. However, the genset frequency may then drop below an acceptable value of the grid frequency.
A variable speed genset may be used to improve the efficiency of the engine. Other advantages of variable speed gensets are reduced fuel consumption, reduced noise, prolonged engine life, and reduced emissions. One challenge for variable speed gensets as well as for fixed speed gensets is that, when there is a step change or a step increase in a load on the genset, the engine may take time to accelerate to its required speed. The time delay may result in poor transient performance or poor transient response of the engine. A variable geometry turbocharger is sometimes used to improve the transient response of the engine. However, such turbochargers are expensive and are not easily obtainable.
Therefore, it would be desirable to have a system and a method that will address the foregoing issues.